/* vim:set ts=2 sw=2 sts=2 et: */
/**
 * \author     Marcus Holland-Moritz (github@mhxnet.de)
 * \copyright  Copyright (c) Marcus Holland-Moritz
 *
 * This file is part of dwarfs.
 *
 * dwarfs is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * dwarfs is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with dwarfs.  If not, see <https://www.gnu.org/licenses/>.
 */

#pragma once

#include <condition_variable>
#include <mutex>

namespace dwarfs {

class semaphore {
 public:
  semaphore(int count = 0)
      : count_{count} {}

  void release() {
    std::unique_lock<std::mutex> lock(mx_);
    ++count_;
    cv_.notify_one();
  }

  void acquire() {
    std::unique_lock<std::mutex> lock(mx_);
    while (count_ == 0) {
      cv_.wait(lock);
    }
    --count_;
  }

 private:
  std::mutex mx_;
  std::condition_variable cv_;
  int count_;
};

} // namespace dwarfs
